Recoil stock

ABSTRACT

A rubber membrane is sealed between a pair of front and back plates forming a fluid filled chamber secured to the butt end of a gun stock. The shock caused by the firing of the gun is translated to the fluid chamber causing the rubber membrane to expand radially with respect to the gun axis resulting in relative movement of the front and back plates toward each other to absorb and relieve the user of the shock impact. A pair of spring loaded pistons longitudinally positioned between the front and back plates provide proper realignment of the recoil pad after firing. A U-shaped spring clamp prestresses the fluid chamber to provide immediate shock absorbing expansion of the membrane when the gun is fired.

[111 3,714,726 [451 Feb. 6, 1973 lO/l909 Schmidt.................i.................42/74 ABSTRACT A rubber membrane is sealed between a pair of front iate shock absorbing expansion of the membrane when the gun is fired. a

11 Claims, 4 Drawing Figures Primary Examiner-Benjamin A. Borchelt Assistant Examiner-CT. Jordan Attorney- Price, Heneveld, l-luizenga & Cooper and back plates forming a fluid filled chamber secured to the butt end of a gun stock. The shockcaused by the firing of the gun is translated to the fluid chamber causing the rubber membrane to expand radially with respect to the gun axis resulting in relative movement of the front and back plates toward each other to absorb and relieve the user of the shock impact. A pair of spring loaded pistons longitudinally positioned between the front and back plates provide proper realignment of the recoil pad after firing. A U-shaped spring clamp prestresses the fluid chamber to provide immed Paul E. Braun, 8325 SW. Miami, Fla. 33143 Nov. 25, 1970 References Cited RECOIL STOCK Inventor:

Filed:

Appl. No.: 92,559

Field of UNITED STATES PATENTS United States Patent Braun l,246,ll7 2,438,142

RECOIL STOCK BACKGROUND OF INVENTION This invention relates to a novel recoil device particularly adapted for use with a gun stock.

The advent of lighter fire arms has intensified the need for an efficient mechanical shock absorber which is both practical and economically feasible. The prior art suggests various devices which force the hydraulic fluid through a restricted passageway or orifice to absorb the shock. These proposals have proven to be complex in their structure and expensive as well as difficult to assemble. In addition, they have proven inadequate in properly realigning or repositioning the absorbing mechanism after firing. Failure to do so adversely affects the accuracy of the gun.

In addition, a common drawback to existing proposals has been the fact that they are built completely into the gun stock and hence not easily adaptable to older existing firearms. Also, where a 'replacement is required, the entire stock must then be replaced.

SUMMARY OF INVENTION The recoil device provided by this invention is comprised of a fluid filled chamber having plate means and expansion means so that when the gun is fired, the shock acting on the chamber causes the expansion means to expand radially with respect to the barrel axis permitting the end plate means to move axially toward each other to provide relief to the shoulder of a person firing the gun. In addition, novel means are provided for resetting and realigning the end plate means and chamber after the weapon is fired so that it can beaccurately fired again.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary view in elevation of the recoil device provided by this invention;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1; and

FIG. 4 is an enlarged cross-sectional view of the encircled portion shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, FIG. 1 shows the recoil pad proposed by this invention mounted to the butt end of a gun stock 12. The pad is mounted to the stock by a pair of screws 14 which fit radially with respect to the gun axis through counterholes 16. A frontal plate 20 having a pair of axially extending brackets 18 are threadably engaged by screws 14 to join the pad to the stock. The screw head 15 seats on the bottom surface 17 of the counterholes to draw the bracket up tight against the stock. The butt end of stock 12 is cut out to permit insertion of brackets 18 to provide positive mounting of the pad to the stock.

A fluid filled chamber 22 is defined by a pair of front plates 24, 26 and a pair of end plates 28, 30. The plates form the respective ends of the chamber while the sides are comprised of a flexible membrane 32 which is joined along the periphery of the plates as follows. The

plates are generally oval in shape (FIG. 2) to conform to the lateral cross section of the gun stock and recoil pad. Each plate includes a continuous groove 34 along the peripheral edge so that when frontal plates 24, 26 and end plates 28, 30 are positioned in facial abutment, grooves 34 form an O-ring groove 36 as shown in FIG. 4. A pair of O-rings 38, 38are integrally formed with the membrane and depend from the interior surface of the membrane along its edges. O-rings 38, 38 are compressed into-groove 36 whenthe end and frontal plates are joined together to provide'a fluidtight seal between the plate and membrane. The compression fit is provided by a plurality of threaded set screws 40 which join the pair of front and end plates together as shown in FIG. 1.

Preferably, the chamber is filled with an incompressible liquid such as an hydraulic fluid to provide recoil or shock absorbing relief as follows. When the gun is fired, the recoil shock from the gun travels down the stock or gun axis toward the shooters shoulder, causing the stock to move abruptly rearward. As the stock moves backward, the shock or compression force is translated to the liquid in the chamber, but since the preferred fluid is incompressible, an equal pressure is exerted in all directions through the fluid. As a result of the resilient and expandible characteristics of the membrane, and the inflexibility of the end and front plates, the pressure exerted through the fluid causes the membrane to expand radially or outwardly with respect to the gun axis. This expansion permits joint movement of the front and end plates toward each otherv thereby providing shock absorption relief for the shooters shoulder. Preferably, the membrane is comprised of rubber which has been found to provide excellent resilient characteristics.

Preferably, the chamber and membrane are covered with a decorative rubber hood 42 which is flexible to fit over various sized stocks when the device is installed in different sized stocks. Additionally, if the hood is too large, portions can be trimmed from the sides or inner end of the hood to conform to the particular size of the stock. A spacing 44 between the hood and membrane is provided around the membrane so that when the gun is fired and the membrane expands, there r is sufficient room for it to expand. I

It has been found that inthe use of a flexible membrane such as that described above, it is advantageous in order to provide a linear type shock absorbing movement of the pad with respect to time that the chamber be slightly prestressed. That is, if the chamber is not sufiiciently prestressed, upon the firing of the gun, there is a tendency for the pad to slightly mushroom prior to full shock absorbing exertion onthe pad. This provides an uneven relief for the shooter and can affect the accuracy in firing the gun. Thus, inorder to provide positive response of the absorbing chamber at the inception of the shock, the chamber is preferably prestressed slightly by a U-shaped clip spring 46 which exerts a slight inward or compression setting force on the membrane thereby slightly prestressing the membrane. This prestressing of the membrane eliminates the possibility of any lag time resulting from being unable to completely fill the chamber with the hydraulic fluid. As a result, a rapid and yet smooth continuous shock absorption is provided. I

After firing, the resiliency of the rubber membrane will bias the plates back into a normal or preset alignment in preparation for the next firing. However, the accuracy of the gun is in part dependent on the proper realignment of the plates and this alignment cannot be completely assured by the resiliency of the membrane alone in light of the normal shock magnitude. Thus, a means is preferably provided for positively resetting the plates into accurate alignment.

The realignment means is provided by a pair of spring biased pistons 50, only one of which is shown in detail in the drawings. The pistons are spaced laterally and mounted through the front plates 20, 24 and 26 to project into the gun stock. Describing the upper piston mechanism in detail (shown in FIGS. 1 and 3), piston 50 is comprised of two portions, a main shaft 51 which is anchored in end plates 28 and 30 by threaded engagement therewith and a necked down or reduced cross section portion 70 which forms a piston chamber 52 and extends through the piston body 54 into the gun stock. The piston or chamber body 54 is comprised of a cylindrical means extending into a counterbore 56 in the stock with the front end of the cylinder in abutment with the bottom surface 58 of the counterbore. Counterbore 56 has an additional reduced cross-sectional portion 72 which extends further into the stock and is provided to receive portion 70 of the piston shaft.

Piston cylinder 54 is secured within the counterbore by a spring 74 mounted between end plates 28, 30 and the cylinder itself, spring 74 encircling the main shaft portion 51 of the piston. Spring 74 thus biases the cylinder into a fixed position relative to the gun stock. Piston 50 slides relative to cylinder 54 and the gun stock and is sealed to prevent any hydraulic fluid from entering into chamber 52 by an O-ring 76 mounted in an O-ring groove 78 provided on the main shaft portion 51 of the piston. This prevents any fluid from entering chamber 52 and hence a seal is not required where the necked down portion 70 of the piston passes through piston cylinder 54 into the gun stock.

Cylinder 54 is sealed with respect to the frontal plates in a fashion similar to the connection of membrane 32 to the front and end plates. An annular groove 60 is provided on the outer periphery of cylinder 54 for receipt of an annular rubber sealing ring 62 which has an O-ring type projection 64. Projection 64 is compressed into sealing engagement between front plates 24 and 26 which plates include a continuous groove 66 and 69, respectively, to form an O-ring groove 68 when the plates are in facial abutment. Again, the O-ring projection 64 is preferably integral with the sealing ring 62. The reason for the axial width of sealing ring 62 is to provide sufficient give between the piston 50 and cylinder 54 so that when the gun is butted up against the shooters shoulder, the piston and cylinder do not become cocked out of alignment. Each shooter varies considerably as to how and how hard he grips the gun. Therefore, ring 62 compensates for this so that the operation of piston 50 is smooth and hence accurate.

Thus, as the gun is fired, and the liquid filled chamber provides shock absorption, piston 50 moves axially forward with respect to front plates 24, 26 and stock 12 in unison with end plates 28 and 30. At the same time sprig 74 is compressed between end plate 28 and the piston cylinder to provide the proper bias required for accurate realignment after firing. In addition to the piston and spring arrangement providing the proper amount of resilient urging necessary to realign the pad after firing, they also act as a damper during firing to damp the movement of the shock absorption liquid filled chamber in respective boot 32. This facilitates a smooth operation of the recoil pad and prevents excessive oscillation which could affect the accuracy of the gun. It also provides for a rigid pad so that it can be firmly seated on the shoulder of the user.

The recoil pad provided by this invention is extremely simple to adapt to any existing gun stock. Of equal importance, the entire mechanism is extremely straight forward in operation and therefore not subject to jamming or cocking when it is realigned after firing.

Although but one embodiment has been shown and described in detail, it will be obvious to those having ordinary skill in this art that the details of construction of this particular embodiment may be modified in a great many ways without departing from the unique concepts presented. It is therefore intended that the invention is limited only by the scope of the appended claims rather than by particular details of construction shown, except as specifically stated in the claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

l. A shock absorbing recoil device adapted to be secured to the butt end of a gun comprising, in combination, a chamber means filled with a generally incompressible fluid, said chamber means having front and rear spaced end wall portions and an annular side wall, said front and rear wall portions having a normal spacing therebetween except when said gun is tired, at least said side wall being comprised of a resilient and flexible membrane so that when said gun is fired, the recoil shock is absorbed by the radial expansion of said membrane with said normal spacing between said front and rear wall portions being reduced.

2. A shock absorbing recoil device adapted to be secured to the butt end of a gun comprising, in combination, a fluid filled chamber means, said chamber having a first and second plate means spaced axially with respect to the gun axis, said plate means forming the ends of said chamber, and a flexible membrane secured to the periphery of said plate means, said membrane forming the sides of said chamber, one of said first and second plate means movable axially with respect to the other between a set position wherein said recoil device is ready in preparation for said gun to be fired and a recoil position wherein said second plate means is in closer proximity to said first plate means and said flexible membrane has expanded radially with respect to said gun axis due to the displacement of the fluid, said membrane expansion absorbing the shock resulting from the firing of said gun causing the fluid to displace.

3. The combination according to claim 2 wherein said fluid is comprised of an incompressible liquid, and said flexible membrane is comprised of a resilient rubber.

4. The combination according to claim 2 wherein said combination is further characterized as including a realignment means cooperating with said first and second plate means urging said plate means into said set position.

5. The combination according to claim 4 wherein said alignment means is comprised of a spring loaded piston-cylinder mounted between said first and second plate means, said alignment means providing a damper for said chamber movement when said gun is fired, and further biasing said plate means into their set position after said'gun is fired.

6. The combination according to claim 5 wherein said combination is detachably mounted to said gun stock to permit removal therefrom, said combination further including a boot surrounding said chamber and adaptable to fit various sized gun stocks, said boot being in part spaced from said membrane to permit the expansion of said membrane to absorb said gun shock.

7. The combination according to claim 2 wherein means are provided for prestressing said chamber to reduce any lag time resulting in said chamber compression and expansion when said gun is tired.

8. The combination according to claim 7 wherein said prestress means is comprised of a U-shaped clip spring disposed around a portion of said membrane, said U-shaped clip exerting a compressive force on said membrane to prestress it.

9. The combination according to claim 1 wherein said combination is further characterized as including an alignment means cooperating with said first and second wall portions to urge said wall portions into said normal spacing.

10. The combination according to claim 9 wherein said alignment means is comprised of a spring loaded piston-cylinder mounted between said first and second wall portions, said alignment means providing a damper for said chamber movement when said gun is fired, and further biasing said wall portions into their normal spacing after said gun is fired.

11. The combination according to claim 1 wherein means are provided for prestressing said chamber to reduce any lag time resulting in said chamber compression and expansion when said gun is fired. 

1. A shock absorbing recoil device adapted to be secured to the butt end of a gun comprising, in combination, a chamber means filled with a generally incompressible fluid, said chamber means having front and rear spaced end wall portions and an annular side wall, said front and rear wall portions having a normal spacing therebetween except when said gun is fired, at least said side wall being comprised of a resilient and flexible membrane so that when said gun is fired, the recoil shock is absorbed by the radial expansion of said membrane with said normal spacing between said front and rear wall portions being reduced.
 1. A shock absorbing recoil device adapted to be secured to the butt end of a gun comprising, in combination, a chamber means filled with a generally incompressible fluid, said chamber means having front and rear spaced end wall portions and an annular side wall, said front and rear wall portions having a normal spacing therebetween except when said gun is fired, at least said side wall being comprised of a resilient and flexible membrane so that when said gun is fired, the recoil shock is absorbed by the radial expansion of said membrane with said normal spacing between said front and rear wall portions being reduced.
 2. A shock absorbing recoil device adapted to be secured to the butt end of a gun comprising, in combination, a fluid filled chamber means, said chamber having a first and second plate means spaced axially with respect to the gun axis, said plate means forming the ends of said chamber, and a flexible membrane secured to the periphery of said plate means, said membrane forming the sides of said chamber, one of said first and second plate means movable axially with respect to the other between a set position wherein said recoil device is ready in preparation for said gun to be fired and a recoil position wherein said second plate means is in closer proximity to said first plate means and said flexible membrane has expanded radially with respect to said gun axis due to the displacement of the fluid, said membrane expansion absorbing the shock resulting from the firing of said gun causing the fluid to displace.
 3. The combination according to claim 2 wherein said fluid is comprised of an incompressible liquid, and said flexible membrane is comprised of a resilient rubber.
 4. The combination according to claim 2 wherein said combination is further characterized as including a realignment means cooperating with said first and second plate means urging said plate means into said set position.
 5. The combination according to claim 4 wherein said alignment means is comprised of a spring loaded piston-cylinder mounted between said first and second plate means, said alignment means providing a damper for said chamber movement when said gun is fired, and further biasing said plate means into their set position after said gun is fired.
 6. The combination according to claim 5 wherein said combination is detachably mounted to said gun stock to permit removal therefrom, said combination further including a boot surrounding said chamber and adaptable to fit various sized gun stocks, said boot being in part spaced from said membrane to permit the expansion of said membrane to absorb said gun shock.
 7. The combination according to claim 2 wherein means are provided for prestressing said chamber to reduce any lag time resulting in said chamber compression and expansion when said gun is fired.
 8. The combination according to claim 7 wherein said prestress means is comprised of a U-shaped clip spring disposed around a portion of said membrane, said U-shaped clip exerting a compressive force on said membrane to prestress it.
 9. The combination according to claim 1 wherein said combination is further characterized as including an alignment means cooperating with said first and second wall portions to urge said wall portions into said normal spacing.
 10. The combination according to claim 9 wherein said alignment means is comprised of a spring loaded piston-cylinder mounted between said first and second wall portions, said alignmenT means providing a damper for said chamber movement when said gun is fired, and further biasing said wall portions into their normal spacing after said gun is fired. 